# [Tutor] Pure functions in python - need a glimpse of functional programming and recursive functions .

Manprit Singh manpritsinghece at gmail.com
Fri Aug 14 00:42:30 EDT 2020

```Dear sir ,

Consider a problem to find nCr . where nCr = fact(n) / (fact(r) *
fact(n-r)).where fact(x)  is factorial of x.
if i write code like this :

def fact(x):                                                  # Function
definition for factorial
if x == 0:
return 1
else :
return x * fact(x-1)

def comb(n, k):                                            # Function
definition for finding nCr
return fact(n) / (fact(k) * fact(n-k))

calling function comb as written below

comb(7,2)
returns 21.0                                                 # Which is the

Just need to know if function comb is a pure function in this particular
case or not . I have raised this question  because an external function
fact has been called inside the function comb 3 times .

My second question is,  i had  never seen any example of recursive
functions in python official documentation. Is it ok to use recursive
functions in python programming ? Do recursive functions  take/ consume
more or less resources in comparison to other alternatives in python ?

Regards
Manprit Singh
```